Debian Security Advisory

DLA-2648-1 mediawiki -- LTS security update

Date Reported:
11 May 2021
Affected Packages:
Security database references:
In the Debian bugtracking system: Bug 985574, Bug 984664.
In Mitre's CVE dictionary: CVE-2021-20270, CVE-2021-27291, CVE-2021-30152, CVE-2021-30155, CVE-2021-30158, CVE-2021-30159.
More information:

Several vulnerabilities were discovered in mediawiki, a wiki website engine for collaborative work.

  • CVE-2021-20270

    An infinite loop in SMLLexer in Pygments used by mediawiki as one if its lexers may lead to denial of service when performing syntax highlighting of a Standard ML (SML) source file, as demonstrated by input that only contains the exception keyword.

  • CVE-2021-27291

    pygments, the lexers used by mediawiki rely heavily on regular expressions. Some of the regular expressions have exponential or cubic worst-case complexity and are vulnerable to ReDoS. By crafting malicious input, an attacker can cause a denial of service.

  • CVE-2021-30152

    An issue was discovered in MediaWiki. When using the MediaWiki API to protect a page, a user is currently able to protect to a higher level than they currently have permissions for.

  • CVE-2021-30155

    An issue was discovered in MediaWiki before. ContentModelChange does not check if a user has correct permissions to create and set the content model of a nonexistent page.

  • CVE-2021-30158

    An issue was discovered in MediaWiki. Blocked users are unable to use Special:ResetTokens. This has security relevance because a blocked user might have accidentally shared a token, or might know that a token has been compromised, and yet is not able to block any potential future use of the token by an unauthorized party.

  • CVE-2021-30159

    An issue was discovered in MediaWiki. Users can bypass intended restrictions on deleting pages in certain fast double move situations. MovePage::isValidMoveTarget() uses FOR UPDATE, but it's only called if Title::getArticleID() returns non-zero with no special flags. Next, MovePage::moveToInternal() will delete the page if getArticleID(READ_LATEST) is non-zero. Therefore, if the page is missing in the replica DB, isValidMove() will return true, and then moveToInternal() will unconditionally delete the page if it can be found in the master.

For Debian 9 stretch, these problems have been fixed in version 1:1.27.7-1~deb9u8.

We recommend that you upgrade your mediawiki packages.

For the detailed security status of mediawiki please refer to its security tracker page at:

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: